This invention relates to aerosol containers, and more particularly to a 2 piece or 3 piece thin walled, non-barrier type aerosol container.
Thin wall, non-barrier type, aerosol containers are known in the art. See, for example, U.S. Pat. No. 5,211,317 to Diamond et al., and its reissue Re 35,843. It is a feature of containers built in accordance with the teachings of these patents that the sidewall of the container has a relatively thin thickness. In the Diamond et al. patent and its reissue, the container wall thickness is said to be on the order of 0.004-0.005 inches (0.102 mm-0.127 mm).
In un-pressurized containers, it is often possible to distort the sidewall of the container. The Diamond et al. patents, for example, refer to the sidewall being deflected by as much as ¼ inch, if a force of as little as 5-10 pounds is applied to the can prior to filling. Additionally, the can, when empty, is said to be easily crushable by hand pressure. However, the cans can be pressurized in a manner so that at 130° F. (54.4° C.), for example, the pressure does not exceed 120-130 psig. Further, the cans will not burst at one and one-half times this pressure (180 psig). However, the cans cannot be vacuum filled at a vacuum level greater than 18 inches of Mercury because if they are, the container will collapse.
While there are a number of advantages to a container having thin sidewalls (lower material costs, for example), current thin wall can constructions have drawbacks as well. For example, during handling of the container prior to its being filled, even a moderate amount of force can distort or crush the container. This renders the container unusable and adds to the manufacturing cost. Those skilled in the art will appreciate that moderate amounts of force can be inadvertently applied to the container at any of a number of different points during the handling and manufacture process, even though the process is substantially automated.
There is a further problem with larger size containers such as are used for insecticides, wasp and hornet sprays, household starch, household products, etc. Examples of these larger size containers are those referred to in the industry as a 211×612, 211×713, 211×804, 214×714, and 214×804 size containers. These containers are made from steel sheets weighing from eighty to eighty-five pounds (80-85 Lbs) per base box. Smaller size aerosol containers are, for example, made from a steel sheet weighing approximately seventy-three to seventy-five pounds (73-75 Lbs) per base box. Since the steel sheets are all of the same size, the heavier sheets are thicker than the lighter weight sheets. Use of a thicker sheet is necessary to prevent damage to the container caused by handling during manufacture of the container, container collapse during vacuum filling, and crushing by hand before the container is filled. The larger cans are more susceptible to damage not only because they are heavy, but also they have significantly greater exposed area to which unwanted and/or unintended forces can be applied.
It would be advantageous therefore to provide a thin wall aerosol container; however, one which, when unfilled, is not easily distorted and rendered unusable. The container will, when filled, withstand substantial forces without distorting, and meets Department of Transportation (DOT) standards in this regard.